}

    @Override
    public String toString() {
      return "(" + getRowKey() + "," + getColumnKey() + ")=" + getValue();
    }
  }

  /**
   * Creates a transposed view of a given table that flips its row and column keys. In other words,
   * calling {@code get(columnKey, rowKey)} on the generated table always returns the same value as
   * calling {@code get(rowKey, columnKey)} on the original table. Updating the original table